MAX1608 Datasheet, PDF (9/16 Pages) Maxim Integrated Products – Octal SMBus-to-Parallel I/O Expanders

Octal SMBus-to-Parallel I/O Expanders
A
B
C
D
EF
G
t_LOW t_HIGH
SMBCLK
SMBDATA
t_SU:STA tHD:STA
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
E = SLAVE PULLS SMBDATA LINE LOW
t_SU:DAT t_HD:DAT
t_HD:DAT
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO SLAVE
H = LSB OF DATA CLOCKED INTO SLAVE
I = SLAVE PULLS SMBDATA LINE LOW
Figure 3. SMBus Write Timing
H
IJ
K
LM
t_SU:STO t_BUF
J = ACKNOWLEDGE CLOCKED INTO MASTER
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION, DATA EXECUTED BY SLAVE
M = NEW START CONDITION
A
B
C
D
EF
G
t_LOW tHIGH
SMBCLK
H
I
J
K
SMBDATA
t_SU:STA t_HD:STA
t_SU:DAT
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
t_HD:DAT
E = SLAVE PULLS SMBDATA LINE LOW
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO MASTER
H = LSB OF DATA CLOCKED INTO MASTER
Figure 4. SMBus Read Timing
t_SU:DAT
t_SU:STO t_BUF
I = ACKNOWLEDGE CLOCK PULSE
J = STOP CONDITION
K = NEW START CONDITION
data MSB first; therefore, IO7, MASK7, and data 7 bit
correspond to the MSB (first bit of the data byte).
Other Registers
RAP uses the send-byte protocol to resample the
address pins. Do not use read- and write-byte proto-
cols to RAP because data is redirected to NDR1
although the ADD_ pins will be sampled.
SPOR uses the send-byte protocol to resample the
address pins and reset the registers to the POR state.
Do not use read- and write-byte protocols to SPOR
because data is redirected to NDR1 although the func-
tion will be performed.
MFID uses the read-byte protocol to access the ID reg-
ister. Do not use write-byte protocol to MFID because
data is redirected to NDR1.
SMBSUS (Suspend-Mode) Input
The state of the SMBSUS input selects which register
contents (NDR1 or SDR1) are applied to the IO_ pins
and which set of registers are used to mask the inter-
rupts (NDR2, NDR3 or NDR2, SDR3). Driving SMBSUS
low selects the suspend-mode registers, while driving
SMBSUS high selects the normal registers. This feature
allows the system to select between two different I/O
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